1. Field of the Invention
The present invention relates to a camera control technique.
2. Description of the Related Art
Network camera systems in which video captured by a camera is transmitted to a terminal device such as a personal computer or mobile telephone via a network such as the Internet have been widespread in recent years. A user operates a GUI (Graphical User Interface) on the terminal device and specifies the panning, tilt angle and zoom magnification of a network camera to thereby change the shooting direction of the camera (see the specification of Japanese Patent Application Laid-Open No. 10-40185).
Network camera systems are being used in surveillance systems at train stations, hospitals and kindergartens, real-time video distribution systems at tourist attractions, and multi-source video distribution systems for live sports broadcasts. A technique that has been proposed for such video distribution systems assigns the camera control privilege to users at fixed time intervals in which multiple users cannot operate the network camera simultaneously (see the specification of Japanese Patent Application Laid-Open No. 10-42278).
Further, in a case where a plurality of controllable cameras have been deployed in the same region or on the same premises, there is a proposed technique whereby a user changes over the controllable cameras utilizing map information indicating the locations at which the cameras have been installed (see the specification of Japanese Patent Application Laid-Open No. 8-265742).
However, a problem with the prior art is that if the number of controllable cameras is large, camera changeover control is difficult. For example, consider a case where a parent is observing his or her own child by using a network camera system installed at a kindergarten. In this case, when the child is about to move outside the viewing angle of the camera being operated by the parent, it is required that the parent refer to the entire shooting area inclusive of the camera placement information and select a new camera again. With this method, selecting the best camera takes time because of the large number of cameras that are capable of shooting continuously. Further, since a display screen for displaying the entire shooting area is required, control of the display is difficult with a terminal device such as a mobile telephone having a small display area.